I have looked at these 10 to 15 litre electric under sink storage water heaters. Screwfix sell them. They all seem to be around the 1 KW capacity. Does anyone know where a 3 killowatt version is avaialble?
TIA
Ariston do one call the Europrisma EP10UR. This is available in 3kW and 10 (or optionally 15) litres unvented.
Christian.
Thanks. I just spotted that page myself. Thanks for the tip. This model doesn't need a special tap, I hope. Will this model will work at low pressure from a loft tank.
Unfortunately not. It has a minimum 1 bar rating, so would need a shower pump. No mains supply nearby, I presume?
Christian.
I am intrigued - what is this "dripping tap"
John
There is a type mains pressure vented heater that works on the principle that the outlet of the cylinder goes to a special tap where the outlet isn't actually turned on and off. Instead, the special tap actually controls the
*input* to the cylinder. When the tap is on, the cold mains comes into the bottom of the cylinder and hot comes out mains pressure from the top and through the tap. When the tap is off, no water enters the cylinder, but water doesn't come out of the tap because it can't go uphill without a push. It remains safe as it is in a vented condition at all times.Disadvantages of the system are that you must use ugly expensive proprietary taps and the expansion due to the water heating is taken up through the tap dribbling away for 20 minutes, causing the untrained users to attempt to turn the tap off harder, which knackers the tap washer and makes it drip more.
Christian.
What I have is a large cylinder fed from the loft. It doesn't have an immersion bosse for electric backup. I was thinking of using one of these storage water heaters with a 3 kilowatt rating to heat the cylinder. I was thinking of buying a cheap DAB pump for =A326 from BES (it is only for backup so a cheap pump will do) and connect the water heater outlet to the a tee at the top coil connection to the cylinder, and take a pipe off the bottom coil connection of the cylinder to the water heater inlet. This forms a loop through the coil. Put the DAB pump pumping into the water heater with a check valve on it. Will the
6 metre DAB pump enough pressure to operate the Ariston? All it needs is water movement through the Ariston, until the whole cylinder is heated then the Ariston thermostat cuts off the power. I see the Ariston can be set to 80C, so this may make matters better.This is far cheaper, and easier, than a new cylinder.
I aim to have two full bore valves to isolate the pump and water heater.
Sod that. Just stick an immersion on the existing cylinder. You just need a hole saw to make the hole and fit a new boss. MUCH cheaper. MUCH simpler.
Indeed if you are replacing an old immersion that's rusted in, then it is probably simpler to just make a new hole and fit than risk bending the cylinder removing it.
Christian.
The cylinder looks pretty new. That could be anything up to 10 years old. It has the metal covering over the insulation, which means I can't cut the cylinder. It definately does not have an immersion boss in it.
Using the Ariston water heater would give electric backup. Now if I fit a 6 metre pump would that be enough? I think 6 metres means it can pump up to 6 metres vertically up which is about 18 foot.That is about 0.5 bar, so does a 6 metre pump give 0.5 bar pressure?
Why does the Ariston water heater need one bar to operate? It is only a steel cylinder with an element inside switched by a thermostat. Is there some pressure valve that can be taken out on the inlet to the water heater? All the pressure valves can be stripped off as it is not working under high pressure.
Why can't you cut it with a large tank cutter? it will require a larger hole in the outer skin, a correct size hole in the inner (water containing) skin and an immersion heater boss which mounts mechanically rather than solders in. These were common at one time although I haven't seen one around for a couple of years.
Er, NO!!! you _WILL_ fit the supplied pressure relief valve, to avoid potential dangers that you cannot forsee....
Why not just replace with another cylinder instead of faffing around with pumps and water heaters?
Or phone Ariston and see what they have to say about it?
cheers, Pete.
Why? It is fitted on the CH primary circuit. If this is fed off an If an F&E tank then there is "nothing" potentially dangerous that will go wrong. If the immersion overboils it does so into the F&E tank. It could also be taken off the secondary water in the cylinder and a bronze pump used, although the bronze pump may make it too expensive.
The water heater idea is quite good, and cheap enough. This was common in some setups, where they had a tube with an immersion fitted with a flow and return to the main cylinder it was heating. The water flowed through via gravity, Depending on the size of the cylinder, then replacement may be very expensive. I would avoid an Essex flange type of immersion boss.
It is possible to use a 2" immersion and some 2.5" pipe as a tube and connect that to the cylinder directly. A 2" immersion is around £100 and the 2.5" pipes an fitting making it an expensive undertaking.
The makers will probably say no, as usual, when in fact the heater will be operating in better conditions than connected to a high pressure main with scaled water in it. It will have primary secondary water with inhibitor in it, and at low pressure too. But it is worth asking them if it can operate at very low pressures. All it needs is a water flow through it to circulate heat into the coil and heat the secondary fresh water. he flow does not have to be fast
It's this bit that worried me:
Also it's not "impossible" a buildup of sludge/scale won't plug the pipes. These heaters are tested to 12 or 16 bar, and will burst somewhat higher. Not good, especially if next to a cylinder full of boiling hot water.
Leaving out a safety device because you don't understand it is a bit 'Darwinian' to say the least... and leads to more nannying legislation for the rest of us.
Cheap! If he's doing up a house to sell on, why not invest a small amount of money/effort into making it safe?
There's better, easier /and/ more cost effective ways, like use a couple of these in a length of pipe eg:
Still needs a 3 bar pressure relief valve next to them IMO.
They would never agree to leaving off the pressure releif valve for a start....
cheers, Pete.
If you understood CH systems it wouldn't
It is in the primary side with inhibitor inside.
It is on a "vented" system.
The safety device is the oopen vented F&E tank.
It is safe.
£20 each second hand. How much new? So 4 of these would be needed to get around 3kW (4 * 800 = 3.2kW) Do they have a stat on them?Not if it is on an open vented system.
They would never agree to a deviation from what they normally sell they thing, to avoid a setting a precedent. The fact is, that having in primary water with inhibitor, on low pressure mean it will last longer and run better.
Pressure relief valve not required on an open vented system. Some unvented cylinders can be fitted open vented and the pressure relief valves removed. Same thing.
Screwfix sell them. To get 3kW you will need four and that comes to over £120. Then there is no stat, so extra, and then the pipes to make an array, the insulation and the pump. May as well use a 3 kW storage water heater, with stat, insulation, etc and a pump.
TLC sell a 5 litre 3kW storage water heater (less water to heat up and store) for £97 plus VAT
OK.
It means no such thing. You just cut through the outer casing first.
Seriously, cutting the cylinder and sticking in a new boss will be much easier and cheaper than your proposed solution. It will also be more energy efficient.
An immersion costs about 12 quid including overheat cutout thermostat. A boss a couple of quid.
You're talking about using 100 quid's worth of heater, pipework, fittings, pumps, etc. just to make an inferior solution.
Christian.
of heater) @ £122 plus VAT (TLC are never cheap, so worth looking elsewhere). The Zipheaters installation instructions says it is only 2kW so needs clarifying; instructions are often wrong and outdated. .
Plus an expensive tank cutter. I personally would not insert a boss with rubber washers onto a cylinder. I have seen too many of them crumble away. It is best to have them brazed in, but that will upset matters and make it expensive.
Look at the Zip Tudor vented water heater I mentioned in another post. For around £150 for heater and pump you have a solution for backup hot water. This cost of course has to be assessed to be worthwhile. TGB thinks so as he is budgeting around £130 or so.
The Santon Aquarius vented water heater at 3kW and the 7 litres model will do. It can run off a cold tank. It needs a 4 metre head to work. So a 6 metre head pump will be fine as long as the pump is directly pumping into the heater inlet as near as possible. At Plumbworld it is £97 inc VAT plus £5 P*P. Installation instructions are at the Santon site,
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